Early Signs a Dairy Cow Is Unwell: What to Notice Before She Looks Sick

By Dr Duncan Houston

A dairy cow can still walk into the parlour, eat some feed and produce milk while a health problem is developing. The first clue may be a small change in her routine rather than an obviously sick animal.

Perhaps she leaves concentrate behind, takes shorter steps or spends less time chewing her cud. Each change needs context, but several changes together deserve attention.

The aim is to recognise trouble before illness becomes obvious. Some conditions produce subtle behavioural changes; others remain hidden until testing detects them.

Quick Answer

Early signs of illness in dairy cattle include reduced appetite or rumination, an unexpected change in milk production, altered walking or resting behaviour, and changes in manure, breathing or alertness. Compare each cow with her own normal pattern, then check whether other signs support the concern. A persistent change or several abnormalities together warrants prompt assessment, particularly after calving; weakness, inability to stand, severe bloat or breathing difficulty requires immediate veterinary attention.

1. She is less interested in feed

Watch how she approaches and eats her ration. A cow that arrives at the feed area but eats reluctantly, leaves feed behind or has a noticeably emptier rumen may be giving you an early warning.

A fresh cow that loses her appetite needs particular attention. Reduced intake can accompany several illnesses, and poor intake can also worsen her energy deficit. Checking appetite and rumen fill is an established part of fresh-cow assessment.

Check access as well as appetite. Is feed actually within reach? Is a dominant cow blocking her? Is the water trough working? Inadequate water availability can quickly reduce both feed intake and milk production.

2. She is chewing her cud less

Rumination is the process of bringing swallowed feed back into the mouth for further chewing. A sustained reduction can signal reduced intake or a developing health problem.

The useful comparison is with that cow’s usual pattern across time. One glance at a cow that is not chewing tells you very little. Repeated observations or reliable monitoring records are more informative.

Research supports using rumination and activity changes to help identify some metabolic and digestive disorders before routine clinical recognition. However, the timing and reliability vary between conditions and monitoring systems.

3. Her milk production changes unexpectedly

An unexplained fall in yield, or failure to increase production as expected after calving, can prompt an earlier examination.

Compare her with her recent records and stage of lactation. Check whether the change coincides with a different milking interval, incomplete milking, equipment problems or a wider herd change.

A milk drop becomes more concerning when she also eats less, looks dull or moves differently. Milk records are useful screening information, but the cow still needs checking.

4. Her walking changes before she develops an obvious limp

Subtle lameness may appear as shorter or uneven steps, an altered back posture, uneven weight bearing or reluctance to move normally.

Watch cows walking at their own pace on a suitable, non-slip surface. Pay attention to turns and transitions between standing and walking. Pushing the group along makes individual differences harder to assess.

Early mobility changes deserve a closer examination. Record the cow’s identity so she does not disappear back into the herd with the problem unresolved.

5. Her resting or social routine changes

A cow that repeatedly stands when she normally rests, struggles to settle or behaves differently around the group deserves a closer look.

There is no universal rule that a sick cow lies down more. Pain, uncomfortable stalls, heat and illness can affect resting behaviour in different ways. Poor bedding, crowding and difficult cow flow can also change behaviour without identifying a particular disease.

Ask what has changed for the cow and what has changed around her. Cow comfort and health need to be assessed together.

6. Her manure or rumen fill changes

Less manure than usual, unusually dry dung, diarrhoea or a persistently hollow-looking left flank can support concern about intake or digestive function.

Interpret these findings alongside feeding time and recent ration changes. A single loose dung pat does not diagnose ruminal acidosis, and an empty-looking flank alone does not identify the cause.

For example, a displaced abomasum can cause reduced appetite, declining milk production and scant manure. Distinguishing it from other problems requires a veterinary examination.

7. Her breathing changes while she is resting

Notice faster breathing, increased effort, drooling or persistent standing in hot conditions. Heat stress can also reduce intake, rumination and milk production.

If several cows change together, check cooling, ventilation, shade and water availability immediately. A single affected cow, especially one that is dull or off feed, also needs assessment for illness.

Open-mouth or visibly laboured breathing is an emergency sign. Do not move a distressed cow unnecessarily or assume the weather explains everything.

8. Her udder health changes before the milk looks abnormal

Subclinical mastitis means inflammation is present without obvious changes in the milk or udder. Individual somatic cell count records and screening such as the California Mastitis Test can reveal a problem that visual inspection misses.

Clots, watery or discoloured milk, and a hot, swollen or painful quarter are already signs of clinical mastitis.

An abnormal screening result needs interpretation within the herd’s mastitis programme. It does not, by itself, identify the organism or establish which treatment is appropriate.

Why cows around calving need extra attention

The transition into lactation places major demands on the cow. A dedicated daily check during the first two weeks after calving helps identify problems while there is still an opportunity to act early.

Several conditions can initially share the same unhelpfully vague signs:

• Ketosis or hyperketonaemia: elevated ketones may occur without obvious illness. Other cows develop reduced appetite and production. Veterinary screening plans may use blood beta-hydroxybutyrate testing or appropriate milk or urine tests.

• Hypocalcaemia: low blood calcium can be subclinical. Trembling, unsteadiness, weakness or difficulty standing around calving raises immediate concern.

• Metritis: foul-smelling, watery, reddish-brown uterine discharge accompanied by dullness, reduced appetite or falling milk yield warrants prompt veterinary assessment. Post-calving discharge must be interpreted alongside the cow’s overall condition.

• Displaced abomasum: reduced interest in concentrate, lower milk yield and reduced manure output can overlap with other fresh-cow disorders.

These conditions can occur together. Finding one abnormality should not stop the examination.

How urgently should you act?

What you notice	What it means for your next step
One small change, with the cow otherwise bright, eating and moving normally	Check her and her surroundings promptly. Record the observation and reassess later the same day. Seek advice if it persists or repeats.
Several changes together, persistent poor appetite, dullness or an unexplained milk decline	Arrange same-day veterinary advice or assessment under your herd health plan. Use a lower threshold for cows around calving.
Rapid deterioration, marked weakness, inability to stand, severe abdominal swelling or breathing distress	Contact a veterinarian immediately.

These are practical escalation points, not a way to diagnose the disease. A rapidly worsening cow should not wait for the next scheduled check.

When is this an emergency?

Call your veterinarian immediately if a cow:

• Cannot rise, collapses or becomes markedly weak or unsteady.

• Has open-mouth breathing or struggles to breathe.

• Develops rapid swelling of the left abdomen with distress, which can indicate life-threatening bloat.

• Becomes severely depressed or weak alongside abnormal milk, udder swelling or foul uterine discharge.

Keep her calm and minimise unnecessary movement while help is arranged. Do not force an oral drench into a weak cow or one that cannot swallow normally, because fluid can enter the lungs.

A practical routine when a cow seems “not quite right”

1. Observe before disturbing her. Watch her breathing, stance, awareness, feeding and movement.

2. Identify and record. Note her number, time, days since calving, recent milk trend and the specific change. “Left half her concentrate and took short steps” is more useful than “looked off”.

3. Check the surroundings. Inspect feed, water, footing, bedding and heat exposure. Look for similar changes in other cows.

4. Carry out your established checks safely. Trained staff may check rectal temperature, examine milk and assess gait or rumen fill using the farm’s agreed procedures. Avoid unsafe handling.

5. Escalate and follow through. Give the veterinarian the observations and relevant history. Assign someone to recheck the cow and document whether she improves or deteriorates.

The published normal rectal temperature range for adult dairy cattle is approximately 38.0 to 39.3°C. Temperature must be interpreted alongside heat exposure, activity and the rest of the examination.

A normal temperature does not rule out illness. Ketosis, displaced abomasum and hypocalcaemia may occur without fever. A temperature reading should support the examination rather than become the entire decision.

Can collars and other monitoring systems notice problems earlier?

Monitoring systems can help reveal changes that are difficult to observe continuously. Depending on the device, they may measure activity, rumination or lying behaviour; milk recording systems add another useful trend.

Choose how to interpret alerts according to what the system actually measures and how well it has been validated. An alert should trigger a check of the cow and her records.

False alerts and missed cases occur. Research on rumination-based health screening shows that performance depends on the approach and setting. An alert is not a diagnosis, and no alert is not an all-clear.

Technology is most useful when someone is responsible for checking alerts and acting on the findings.

Common mistakes that delay recognition

• Waiting for complete feed refusal. Reduced interest in feed already deserves attention.

• Relying on the bulk tank. A herd total can conceal a problem in one cow.

• Treating a sensor alert as a diagnosis. Examine the cow before deciding what the alert means.

• Assuming every change is an infection. Nutrition, pain, heat and metabolic disease also need consideration.

• Recording a concern without arranging a recheck. A useful observation needs a named person and a next step.

Make early detection part of everyday management

Support normal feeding and resting with reliable water access, appropriate feed space, comfortable bedding, good ventilation and calm handling. Reduce avoidable competition and make it easy for cows to move through the dairy.

Review transition feeding and fresh-cow monitoring with your herd veterinarian and nutritionist. Consistent observation, clear records and staff who recognise changes in individual cows make the daily routine more useful.

Can a dairy cow be sick while still eating and producing milk?

Yes. Partial appetite and ongoing milk production do not establish that she is healthy. Look at changes in intake, yield, movement and behaviour together.

Does less cud chewing always mean disease?

No. Feeding patterns and other circumstances affect rumination. A sustained change from her usual pattern, particularly with other abnormalities, deserves checking.

Can a cow be unwell without a fever?

Yes. Several metabolic and digestive conditions occur without a raised temperature. Assess the whole cow.

Can every illness be spotted before visible signs develop?

No. Some problems develop rapidly, and genuinely subclinical conditions may require testing. Observation, records and targeted screening work best together.

When a familiar cow starts behaving differently, record exactly what has changed and check her promptly. Several small abnormalities, especially around calving, are enough reason to seek veterinary advice before the picture becomes more obvious.

ASK A VET™ encourages informed observation and timely veterinary care. Keep your herd veterinarian involved in unexplained changes, and contact them directly when a cow needs urgent attention.